Stabilized nitromannite product and method of making the same



f'atenteci Nov. 4, 1952 STABILIZED NITROMANNITE PRODUCT AND METHOD OF MAKING THE SALE Joseph W. Lawrence, Tamaqua, Pa., assignor to Atlas Powder Company, Wilmington, Del., a

corporation of Delaware Serial No. 231,901

No Drawing. Application June 15, 1951,

15 Claims. 1

The present invention relates to an improved nitromannite product; and, more particularly, it relates to a pentanitromannite or hexanitromannite product possessing markedly increased thermal stability. The invention also relates to a method for preparing the novel product as well as to a method for stabilizing pentanitromannite and hexanitromannite.

Hexanitromannite has been used in commercial detonators for many years. While this compound has sufficient stability for use in certain industrial applications in that under ordinary conditions it may last for many weeks without decomposing substantially, it rapidly decomposes at elevated temperatures so that there is always the danger that, in the event the explosive becomes subjected to elevated temperatures, the hexanitromannite will decompose to some extent thus rendering the explosive defective. In situations where elevated temperature conditions may normally be encountered, the instability of the hexanitromannite prevents its use. For use in detonators for military purposes, moreover, hexanitromannite is of such insufiicient thermal stability as to be of very limited use. The problems of instability with respect to pentanitromannite are similar to those encountered with hexanitromannite.

A principal object of the present invention is to provide a hexanitromannite or pentanitromannite product possessing vastly improved stability at elevated temperatures.

Another object of the present invention is to provide a hexanitromannite product sufficiently stable thermally to be employed in detonators having wider applicability for both military and industrial purposes.

Still another object of the present invention is to provide a method for preparing the novel stabilized hexanitromannite or pentanitromannite product.

A further object is to provide a method of stabilizing hexanitromannite and pentanitromannite.

The novel stabilized nitromannite product of the present invention comprises at least one of the nitromannites selected from the group consisting of hexanitromannite and pentanitromannite, and a small eifective amount of ammonium mucate intimately mixed therewith.

Since, of the nitromannites mentioned, hexanitromannite is the one most commonly employed in the explosives field, the stabilization represents the preferred embodiment of the present invention, and the invention will be described with particular emphasis thereon. However, it will be realized that the invention may also be applied to the stabilization of pentanitromannite, and to mixtures of hexanitromannite and pentanitromannite.

It has been found that the mixing of a minor amount of ammonium mucate with hexanitromannite provides a product which possesses unusually improved thermal stability. This improved thermal stability, moreover, is many times greater than that provided, for example, when other ammonium compounds are intimately mixed with hexanitromannite.

Hexanitromannite, as is well known, is prepared by nitrating mannitol to provide a nitromannite product consisting substantially entirely of hexanitromannite with small but varying proportions of other nitromannites, particularly pentanitromannite, and of other impurities. The purity of the hexanitromannite product may vary somewhat depending upon the particular procedure and technique employed in its preparation, and the present invention is applicable to any of the commercial forms of hexanitromannite as well as to relatively pure hexanitromannite. It will be understood, therefore, that herein and in the claims, the term hexanitromannite will refer to somewhat impure commercial hexanitromannite products as well as to relatively pure forms of hexanitromannite.

As stated above, the compound intimately mixed with the nitromannite to impart the improved thermal stability in accordance with the present invention is ammonium mucate. This compound is an ammonium salt of music acid, which acid is also known as 2,3,4,5-tetrahydroxy hexanedioic acid, the formula of which is COOH(CHO-H) 4COOH The ammonium salt employed in accordance with the present invention is the diammonium salt produced by replacing the two acid hydrogens with the ammonium radical. The empirical'formula for the salt may be written as N H4) aCeI-IaOs In the preparation of the product of the present invention it is necessary that the ammonium mucate be intimately mixed with and thoroughly dispersed in the nitromannite. Various methods for accomplishing this will occur to those skilled in the art. A preferred method comprises depositing the ammonium mucate on the hexanitromannite particles by wetting the hexanitromannite, which is insoluble in water, with an aqueous solution comprising the ammonium mucate. Upon drying, the ammonium mucate will be deposited on and intimately mixed with the hexanitromannite particles. In this regard, a particularly advantageous method of incorporating the ammonium mucate in the hexanitromannite comprises precipitating the hexanitromannite in an aqueous solution comprising the ammonium mucate. For instance, the hexanitromannite may be dissolved in a suitable solvent therefor, such as acetone, methyl alcohol, ethyl alcohol, methyl formate, methyl acetate, and the like. The concentration of the hexanitromannite may vary between about and about 70%, by weight. The resulting solution may then be added to an aqueous solution of the ammonium mucate, for example, in a ratio of between about 5 and about parts by volume of the hexanitromannite solution per 100 parts by volume of the ammonium mucate solution, whereby the hexanitromannite precipitates. The precipitated hexanitromannite may be separated from the aqueous medium as by'filtering, centrifuging, and the like. Upon drying the precipitate, a very intimate mixture of the ammonium mucate with the hexanitromannite is provided.

More than one application of the aqueous solution of ammonium mucate to the hexanitromannite may be resorted "to, if necessary or desirable. For instance, in the above-described precipitation procedure the precipitate, upon separation from the solution, may be further treated with an aqueous solution of ammonium mucate followed by drying.

The proportions of ammonium mucate intimately mixed with the nitromannite, in accordance with the present invention, may vary somewhat depending upon the increase in thermal stability desired in any particular case. The amount required to be effective for the purpose of increasing stability is small, and, in general, the amount of ammonium mucate associated with the nitromannite will be at least about 0.5% and may be as high as about 3%, by weight, based on the weight of the nitromannite. Preferably the ammonium mucate is associated with the nitromannite in an amount between about 1 and about 2%, by weight, based on the weight of the nitromannite.

When the ammonium mucate is associated with the nitromannite by a deposition procedure of the type described above, the concentration of the ammonium mucate in the aqueous solution, and the amount of solution employed will be such as to provide the desired proportion of ammonium mucate in the final product. In general, in such a procedure, it may be said that the proportion of ammonium mucate in the final product may vary directly with the concentration thereof in the aqueous solution; and the concentration of ammonium mucate in the aqueous solution, for any particular proportion thereof in the final product, can easily be ascertained. For example, to provide an amount of ammonium mucate in the final product of about 1-2%, an aqueous solution containing about 3%, by weight, of the ammonium mucate has been found to be suitable (on the basis of 100 cc. of solution per 3 grams of hexanitromannite).

The product of the invention and its prepara tion, and the method of stabilizing hexanitromannite and pentanitromannite in accordance with the present invention, will be more easily understood from a consideration of the following specific examples which are given for the purpose of illustration and are not intended to limit the scope of the invention in any way:

EXAMPLE I Three grams of commercial hexanitromannite are dissolved in 10 cc. of acetone. The resultin solution is added to cc. of a 3%, by weight, aqueous solution of ammonium mucate. During the addition, the solution is stirred vigorously, facilitating the formation of a finely-divided precipitate. The final mixture is filtered and the residue is washed with 100 cc. of a 3%, by weight, aqueous solution of ammonium mucate.

The product is then dried for several hours at room temperature. The product contains about 1-2%, by weight, of ammonium mucate based on the weight of the hexanitromannite.

The product prepared in accordance with the above was tested for thermal stability as follows: It was pressed into a detonator cap at a 25 lb. pin pressure. The resulting assembly was then heated to 78 C. and held at this temperature to determine how long it would take for the sample to completely decompose. After days, the sample still had not completely decomposed whereas a sample of hexanitromannite without the ammonium mucate, when tested in the same way, completely decomposed in only 1 days.

Mixtures were prepared in the same manner as described above, with, however, 20 ammonium salts other than ammonium mucate to compare their stabilizing power toward hexanitromannite with that of ammonium mucate. The various samples were tested in the same manner as described above and the results of all the tests are set forth in the following table.

Table I Ammonium compound Time for sample to decomemployed: pose completelydays None 1 Ammonium mucate 120 Ammonium acetate 2 Ammonium oxalate 85 Di ammonium phosphate 20 Ammonium phosphate 25 Ammonium molybdate 9 Ammonium nitrate 2 Copper ammonium sulphate 1 Ferric ammonium sulphate Ammonium sulfamate 10 Ammonium sulphate--- 1 Ammonium chloride 1 Ammonium arsenate 2' Ammonium citrate 23 Ammonium formate 3 Ammonium tartrate '6 Ammonium bitartrate Ammonium borate Ammonium thiocyanate 5 Ammonium chromate Ammonium benzoate 1 It will be noted from the above that some of the ammonium salts such as, for example-ferric ammonium sulphate, ammonium ditartrate, ammonium borate, and ammonium chromate, actually catalyzed the decomposition of the hexanitromannite. The other ammonium salts increased the stability of the hexanitromannite by varying degrees, but none of them improved the stability to the extent provided by ammonium mucate. From the foregoing it will be seen that it is not possible to give an accurate explanation of the mechanism by which the marked stability of the hexanitromannite is provided by the ammonium mucate.

EXAMPLE II suspension is then filtered and the residue is' washed with 100 cc. of a 3% aqueous ammonium mucate solution. The product is then dried overnight at room temperature. The resulting dried product contains 1-2% ammonium mucate.

Considerable modification is possible in the selection of the proportions of ammonium mucate associated with the nitromannite as well as in the particular method of associating the ammonium mucate with the nitromannite with out departing from the scope of the invention.

I claim:

1. An explosive composition comprising at least one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite, and a small amount of ammonium mucate intimately mixed therewith.

2. The product of claim 1 wherein said nitromannite is hexanitromannite.

3. The product of claim 2 wherein said ammonium mucate is present in an amount between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

4. The product of claim 2 wherein said ammonium mucate is present in an amount between about 1% and about 2%, by weight, based on the Weight of said hexanitromannite.

5. The method of stabilizing at least one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite which comprises intimately mixing a small effective amount of ammonium mucate therewith.

6. The method of claim 5 wherein said nitromannite is hexanitromannite.

7. The method of claim 6 wherein the amount of ammonium mucate intimately mixed with said hexanitromannite is between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

8. The method of claim 6 wherein the amount of ammonium mucate intimately mixed with said hexanitromannite is between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

9-. The method of stabilizing at least; one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite which comprises wetting said nitromannite with a solution of ammonium mucate in a solvent in which the nitromannite is substantially insoluble, and drying the nitromannite.

10. The method of claim 9 wherein the said nitromannite is hexanitromannite and wherein the amount of said solution and the concentration of ammonium mucate therein provides, in the dried product, ammonium mucate in an amount between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

11. The method of claim 9 wherein the said nitromannite is hexanitromannite and wherein the amount of said solution and the concentration of ammonium mucate therein provides, in the dried product, ammonium mucate in an amount between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

12. The method of claim 9 wherein said solvent is water.

13. The method of stabilizing at least one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite which comprises precipitating, from a solution thereof, said nitromannite in a solution comprising ammonium mucate in a solvent in which the nitromannite is insoluble, and drying the precipitate.

14. The method of claim 13 wherein said nitromannite is hexanitromannite and wherein the amount of said solution of ammonium mucate and the concentration of ammonium mucate therein provides, in the dried product, ammonium mucate in an amount between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

15. The method of claim 13 wherein the nitromannite is hexanitromannite and wherein the amount of said solution of ammonium mucate and the concentration of ammonium mucate therein provides, in the dried product, ammonium mucate in an amount between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

JOSEPH W. LAWRENCE.

No references cited. 

1. AN EXPLOSIVE COMPOSITION COMPRISING AT LEAST ONE OF THE NITROMANNITES SELECTED FROM THE GROUP CONSISTING OF PENTANITOMANNITE AND HEXANITROMANNITE, AND A SMALL AMOUNT OF AMMONIUM MUCATE INTIMATELY MIXED THEREWITH. 